1. Field of the Invention
The present invention relates to a printed circuit assembly in a device such as a camera, for example, in which various mechanical parts are compacted in a housing and various electrical parts are distributedly arranged in very restricted spaces between the mechanical parts and the housing, the printed circuit assembly being provided with a highly compacted electric circuit for electrically controlling various operations of said device. Particularly, it relates to improvements in a printed circuit assembly for electrically converting to the above described electric circuit each of the above described electrical parts adapted to be equipped in the very restricted spaces between the above described mechanical parts and the housing.
For the better understanding of the present invention, a description will be given below of the printed circuit assembly of the type described above used in the field of the camera. However, it is apparent that the present invention is not limited to the scope as described below, but it is sufficiently applicable to various field other than the camera.
2. Description of the Prior Art
Speaking of the camera, electronization has recently advanced particularly in the technique of the operation of the exposure, and it has widely practiced to compact various electrical parts in the camera together with the electric circuit forming the main part of the exposure mechanism so as to electrically control various actuations of the exposure mechanism, and such a tendency has been especially remarkable together with the recent development of the IC techniques.
On the other hand, in the field of camera, the minimization of the size of the camera has heretofore been severely desired. Since major portion of the entire volume in the camera housing is occupied by various mechanical parts, only very restricted spaces distributedly formed in the camera housing are left for arranging therein various electrical parts required for electrically controlling various actuations related to the exposure operation as well as the essential electric circuit. Thus, these electrical parts and the essential electric circuit are necessarily distributedly arranged in such very restricted spaces.
Therefore, in a camera of such a type, wiring operation is very troublesome to electrically connect the respective electrical parts distributedly arranged in the camera housing by using lead wires, and the efficiency of assembling the camera is extremely deteriorated. In addition, the damage of the lead wires or failure in the electrical connection thereof will increase. To avoid the above disadvantages, it is desirable that almost all the electrical parts except those which are in direct interface relationship to the mechanical parts of the camera are arranged on the printed circuit chips in the integrated form together with the essential electric circuit so as to make the volume as small as possible, and electrical conductors for electrically connecting the respective electrical parts distributedly arranged in the camera housing to the integrated circuit portion are formed on the printed circuit chips by the printing thereby constructing a so-called printed circuit assembly and the printed circuit assembly is arranged within the very restricted spaces in the interior of the camera.
For example, taking a single lens reflex camera as an example, electrical parts which are in direct interface relationship to the mechanical parts such as various resistors for applying inputs indicative of the film sensitivity, the shutter time, or the diaphragm aperture to the exposure control circuit and switches and electromagnets for controlling the operation of the shutter mechanism are mainly distributedly arranged in the spaces between the upper side of the mechanical portion in the camera and the upper cover of the camera and between the lower side of the mechanical portion and the bottom cover of the camera, and the essential electric circuit portion effecting the operational calculation of the exposure and the control of the exposure is formed in integrated form and arranged in the space between the pentagonal roof prism and the upper cover of the camera, and these portions are electrically connected by means of flexible printed circuit chips.
In the printed circuit assemblies of the type described above, when it is intended to form the printed circuit chip in a single continuous base plate, it is necessary to arrange the printed circuit chip in variously bent form so as to extend from the upper side of the mechanical portion through the front side thereof to the lower side of the mechanical portion, in order to effect efficient connection of the various electrical parts distributedly arranged in the upper and lower sides of the mechanical portion to the essential electric circuit. Particularly, it is almost impossible to arrange the printed circuit chip passing across the front side of the mechanical portion so as to be located at the side surface of the mechanical portion.
Therefore, in case the printed circuit chip is formed as a single continuous base plate, the configuration of such a printed circuit chip when extended in a plane must necessarily be in the L-shape thereby deteriorating the yield of the material in punching operation for forming the printed circuit chips, because waste portions of the material must be increased due to the L-shape of the printed circuit chip.
In order to eliminate the above described disadvantages, it has been proposed to divide the printed circuit chip into a plurality of sections so as to form them from the material, respectively, and then to join them together by soldering so as to form the printed circuit chip. In this case, troublesome soldering operation is required for electrically connecting the printed conductors at the joined portions of the printed circuit chip. Further, the electrical connection by soldering is less reliable and failure in electrical connection or damage in the electric circuit might occur.
On the other hand, as to the material for producing such flexible printed circuit chips, heat resisting, electrically insulating synthetic resin is used such as polyester group, or polyamide group or the like. These materials are very expensive and, therefore, it will cause obstacles in lowering the price of the camera if the yield of the material for forming the printed circuit chips is made low thereby raising the cost of the printed circuit chips per se.